Chemical structure, antioxidant and anti-inflammatory activities of two novel pectin polysaccharides from purple passion fruit (Passiflora edulia Sims) peel

Two novel pectin polysaccharides were extracted from purple passion fruits (Passiflora edulia Sims) peel by hot-water extraction (PFSP60) and ultrasonic-assisted extraction (UPFSP60), their structural characteristics, antioxidant and anti-inflammatory effects were preliminary investigated. The results revealed that the monosaccharide compositions of both polysaccharides mainly include galacturonic acid, glucose, xylose, arabinose, galactose and rhamnose. Methylation analysis indicated that the main linkage types of PFSP60 included 1,4-linked-GalA, 1,4-linked-Glc, 1,4-linked-Xyl and 1-linked-Gal in a molar ratio of 1.02:1.00:0.36:0.13. The glycosidic linkage types of UPFSP60 included 1,4-linked-GalA, 1,4-linked-Glc, 1,2-linked-Rha, 1,4-linked-Xyl and 1,3,6-linked-Gal in a molar ratio of 4.03:1.00:0.32:0.31:0.29. The DPPH radical, ABTS radical, hydroxyl radical, and superoxide anion scavenging activities of PFSP60 and UPFSP60 enhanced in a dose-dependent manner. In LPS-induced RAW 264.7 macrophages, PFSP60 and UPFSP60 could inhibit secretion amounts of pro-inflammatory factors (NO, IL-1β, TNF-α and IL-6) and down-regulated gene expressions. However, the polysaccharides extracted with the assistance of ultrasonication showed stronger antioxidant and anti-inflammatory activities. The results suggested that ultrasound treatment might be an effective approach to obtain pectin polysaccharides with lower molecular weight and stronger antioxidant and anti-inflammatory activities. These results also indicated that passion fruit peel polysaccharides have potential application prospect in functional foods and medicine industry.